Identification of a CD4-binding site-directed antibody with ADCC activity from a chronic HIV-1B'-infected Chinese donor

A potent and broad CD4 binding site neutralizing antibody with strong ADCC activity from a Chinese HIV-1 elite neutralizer

The discovery of broadly neutralizing antibodies (bNAbs) that target conserved epitopes on the HIV-1 envelope glycoprotein (Env) has garnered significant attention for its potential in the development of effective therapeutic and vaccine strategies. In this study, we isolated and characterized a CD4 binding site (CD4bs) antibody, FD22, from an elite neutralizer in China who had been infected with a clade B virus through contaminated blood plasma for 23 years. The heavy chain of FD22 was derived from a rarely reported IGHV3-30 germline gene and exhibited an exceptionally high degree of somatic hypermutation (SHM) (37%), along with a long and unique CDRH3 loop of 20-amino acids. FD22 exhibited potent and broad neutralizing activity, comparable to that of the well-known bNAb VRC01. It effectively neutralized 82% of a panel of 145 diverse HIV-1 pseudoviruses, including the two major circulating strains in China, CRF01_AE and CRF07_BC. FD22 bound strongly to HIV-1-infected cell lines, efficiently engaged FcγRIIIa receptors, triggered NK cell degranulation and the release of key cytokines such as IFN-γ and β-chemokines, and robustly induced antibody-dependent cellular cytotoxicity (ADCC) against HIV-1-infected target cells. Structural prediction for FD22 and the HIV Env SOSIP trimer performed by AlphaFold3, site-mutagenesis, and autologous virus reverse mutation assays revealed that the epitope of FD22 spans key CD4 binding site, including Loop D, the CD4 binding loop (CD4 BLP), and the V5 Loop. The unique long CDRH3 loop of FD22 interacts with the CD4 binding site through its negatively charged residue R102, distinguishing it from other CD4bs antibodies. Our findings provide valuable insights into the mechanisms of FD22 in viral neutralization and ADCC. The dual functionality of FD22 enhances its potential as a promising therapeutic antibody and offers new avenues for designing CD4bs-targeting vaccines with enhanced ADCC capabilities.

Plasma proteomics analysis of Chinese HIV-1 infected individuals focusing on the immune and inflammatory factors afford insight into the viral control mechanism

Background

Long-term non-progressors (LTNPs) with HIV infection can naturally control viral replication for up to a decade without antiretroviral therapy (ART), but the underlying mechanisms of this phenomenon remain elusive.

Methods

To investigate the relevant immune and inflammatory factors associated with this natural control mechanism, we collected plasma samples from 16 LTNPs, 14 untreated viral progressors (VPs), 17 successfully ART-treated patients (TPs), and 16 healthy controls (HCs). The OLINK immune response panel and inflammation panel were employed to detect critical proteins, and the plasma neutralizing activity against a global panel of pseudoviruses was assessed using TZM-bl cells.

Results

The combination of IL17C, IL18, DDX58, and NF2 contributed to discriminating LTNPs and VPs. IL18 and CCL25 were positively associated with CD4+ T cell counts but negatively correlated with viral load. Furthermore, CXCL9 and CXCL10 emerged as potential supplementary diagnostic markers for assessing the efficacy of antiretroviral therapy (ART). Finally, TNFRSF9 displayed positive correlations with neutralization breadth and Geometry Median Titer (GMT) despite the lack of significant differences between LTNPs and VPs.

Conclusion

In summary, this study identified a set of biomarkers in HIV-infected individuals at different disease stages. These markers constitute a potential network for immune balance regulation in HIV infection, which is related to the long-term control of HIV by LTNPs. It provides important clues for further exploring the immune regulatory mechanism of HIV.

Identification of an IGHV3-53-Encoded RBD-Targeting Cross-Neutralizing Antibody from an Early COVID-19 Convalescent

Since November 2021, Omicron has emerged as the dominant severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant, and its sublineages continue to appear one after another, significantly reducing the effectiveness of existing therapeutic neutralizing antibodies (NAbs). It is urgent to develop effective NAbs against circulating Omicron variants. Here, we isolated receptor binding domain (RBD)-specific single memory B cells via flow cytometry from a COVID-19 convalescent. The antibody variable region genes of the heavy chain (VHs) and light chain (VLs) were amplified and cloned into expression vectors. After antibody expression, ELISA screening and neutralizing activity detection, we obtained an IGHV3-53-encoded RBD-targeting cross-neutralizing antibody D6, whose VL originated from the IGKV1-9*01 germlines. D6 could potently neutralize circulating Omicron variants (BA.1, BA.2, BA.4/5 and BF.7), with IC50 values of less than 0.04 μg/mL, and the neutralizing ability against XBB was reduced but still effective. The KD values of D6 binding with RBD of the prototype and BA.1 were both less than 1.0 × 10-12 M. The protein structure of the D6-RBD model indicates that D6 interacts with the RBD external subdomain and belongs to the RBD-1 community. The sufficient contact and deep interaction of D6 HCDR3 and LCDR3 with RBD may be the crucial reason for its cross-neutralizing activity. The sorting and analysis of mAb D6 will provide important information for the development of anti-COVID-19 reagents.

Characterization of RBD-specific cross-neutralizing antibodies responses against SARS-CoV-2 variants from COVID-19 convalescents

INTRODUCTION

The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has been posing a severe threat to global public health. Although broadly neutralizing antibodies have been used to prevent or treat corona virus disease 2019 (COVID-19), new emerging variants have been proven resistant to these antibodies.

METHODS

In this study, we isolated receptor binding domain (RBD)-specific memory B cells using single-cell sorting method from two COVID-19 convalescents and expressed the antibody to test their neutralizing activity against diverse SARS-CoV-2 variants. Then, we resolved antibody-RBD complex structures of potent RBD-specific neutralizing antibodies by X-ray diffraction method. Finally, we analyzed the whole antibody repertoires of the two donors and studied the evolutionary pathway of potent neutralizing antibodies.

RESULTS AND DISCUSSION

We identified three potent RBD-specific neutralizing antibodies (1D7, 3G10 and 3C11) from two COVID-19 convalescents that neutralized authentic SARS-CoV-2 WH-1 and Delta variant, and one of them, 1D7, presented broadly neutralizing activity against WH-1, Beta, Gamma, Delta and Omicron authentic viruses. The resolved antibody-RBD complex structures of two antibodies, 3G10 and 3C11, indicate that both of them interact with the external subdomain of the RBD and that they belong to the RBD-1 and RBD-4 communities, respectively. From the antibody repertoire analysis, we found that the CDR3 frequencies of the light chain, which shared high degrees of amino acid identity with these three antibodies, were higher than those of the heavy chain. This research will contribute to the development of RBD-specific antibody-based drugs and immunogens against multiple variants.

Characterization of a VRC01-like antibody lineage with immature VL from an HIV-1 infected Chinese donor

Because of the broadly neutralizing activity, VRC01-class antibodies are attractive templates for HIV-1 vaccine development and suitable candidates for HIV-1 therapy. Although we previously revealed that glycans in gp120 may have a role in the uneven evolution of the V_H and the V_L of a VRC01-class antibody, DRVIA7, which was isolated from an elite neutralizer, it is unknown whether the immature V_H or V_L of VRC01-class antibodies are also present in the non-neutralizer. We identified a CD4bs-directed antibody - 263A9 - with low neutralizing activity from a donor whose plasma had a moderate neutralizing spectrum in this study. The 263A9 antibody, in particular, was a VRC01-like antibody whose V_H and V_L were derived from IGHV1-2 * 04 and IGKV1-33 * 01, respectively, and both had significant SHM rates. Surprisingly, we discovered that the V_L of 263A9 hindered the neutralizing activity of the antibody, and that replacing its LCDR1 and LCDR3 with VRC01 increased the neutralizing breadth of the chimeric antibodies. Following that, an antibodyomics research revealed that the V_L of 263A9 lineage was remote from VRC01-class antibodies. We also looked at the envelope sequence characteristics of donor CBJC263 and discovered that N276 in the D loop and N460/N463 glycans in the V5 region of gp120 potentially interact with V_L of 263A9 at the structural level. This study will provide valuable information for immunogen screening and vaccine development for eliciting VRC01-class antibodies. DATA AVAILABILITY STATEMENT: The original data presented in the study are included in the article or Supplementary materials. Further inquiries can be directed to the corresponding author. HIV Env sequences in the manuscript had been deposited into the GenBank with the accession numbers from OL466822 to OL466859.